I'm storing in the user profile a base 64 string that hold some custom data. As the data may be quite heavy, the profile property has been set to allow multiple string values.

However, when the string starts to grow significantly, SharePoint starts to alter the string values. In my case, a single "S" is transformed to a "s". And after that, as I'm deserializing the string, this make the whole thing to crash.

I was not able to understand when does it occurs, but I have written a small reproduction code :